Greetings, I'm intended to update libtool package for MSYS2, but some troubles occurred that beyond my ability. I'm confused by some flags when linking.
Compared to v2.4.7, libtool now accepts more flags when linking. The most of the flags in https://github.com/msys2/MSYS2-packages/blob/master/libtool/0003-Pass-various-runtime-library-flags-to-GCC.mingw.patch were added in v2.5.3. As you can see, there is still some flags automatically ignored by libtool when linking. For example, you can run the following commands in your shell. libtool --version | head -1 echo "void foo(void) {}" >foo.c libtool --mode=compile --tag=CC cc -c foo.c -o foo.lo -O3 -ffast-math libtool --mode=link --tag=CC cc foo.lo -o libfoo.la -O3 -ffast-math -rpath /usr/lib -version-info 0 -no-undefined Here is the output on Arch Linux with libtool v2.5.3 (they prefer uses git instead of the unstable version, so -dirty were append in the version string) libtool (GNU libtool) 2.5.3-dirty libtool: compile: cc -c foo.c -O3 -ffast-math -fPIC -DPIC -o .libs/foo.o libtool: compile: cc -c foo.c -O3 -ffast-math -o foo.o >/dev/null 2>&1 libtool: link: rm -fr .libs/libfoo.a .libs/libfoo.la .libs/libfoo.lai .libs/libfoo.so .libs/libfoo.so.0 .libs/libfoo.so.0.0.0 libtool: link: gcc -shared -fPIC -DPIC .libs/foo.o -O3 -Wl,-soname -Wl,libfoo.so.0 -o .libs/libfoo.so.0.0.0 libtool: link: (cd ".libs" && rm -f "libfoo.so.0" && ln -s "libfoo.so.0.0.0" "libfoo.so.0") libtool: link: (cd ".libs" && rm -f "libfoo.so" && ln -s "libfoo.so.0.0.0" "libfoo.so") libtool: link: ar cr .libs/libfoo.a foo.o libtool: link: ranlib .libs/libfoo.a libtool: link: ( cd ".libs" && rm -f "libfoo.la" && ln -s "../libfoo.la" "libfoo.la" ) As what you saw, -ffast-math were ignored. However, I found that some flags were necessary on some platforms to generate startup code for these flags. See the footnote in the following page. https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#FOOT1 Is there any reason why these flags not included? Is it necessary for linking? If so, could anyone please give me a full list of these flags which are probably necessary for linking? I would really appreciate it if you could give me a hand. Best Regards, Yang Kun
